What ckuri said. Just to be clear, you need the following line of code before opening the stream (steps 2,3):
System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);
ExcelDataReader – Important note on .NET Core
By default, ExcelDataReader throws a NotSupportedException “No data is
available for encoding 1252.” on .NET Core.To fix, add a dependency to the package System.Text.Encoding.CodePages
and then add code to register the code page provider during
application initialization (f.ex in Startup.cs):
System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);This is required to parse strings in binary BIFF2-5 Excel documents
encoded with DOS-era code pages. These encodings are registered by
default in the full .NET Framework, but not on .NET Core.